Try to fix some buildbot failures on test_ssl
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index 7874c24..ba5972a 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -1581,6 +1581,7 @@
     int r;
 
     errno = 0;
+    ERR_clear_error();
     if (!PyArg_ParseTupleAndKeywords(args, kwds,
         "O|O:load_cert_chain", kwlist,
         &certfile, &keyfile))